Vaporizer for the evaporation of metals, especially in high vacua



Aug. 7, 1956 Filed Aug. 9, 1954 J. WEBER VAPORIZER FOR THE EVAPORATION OF METALS, ESPECIALLY IN HIGH VACUA F 1' gal 2 Sheets-Sheet l Fig.2

INVENTOR J. WE BER WW/WA ATTORNEY Aug. 7, 1956 J. WEBER 2,757,788

VAPORIZER FOR THE. EVAPORATION OF METALS, ESPECIALLY IN HIGH VACUA Filed Aug. 9. 1954 2 Sheeis-Sheet 2 INVENTOR J. WEBER W O/M1 ATTORNEY United States Patent VAPORIZER FOR THE EVAPORATION OF NIETAL'S, ESPECIALLY IN HIGH VACUA Joachim Weber, Nurnberg, Germany, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application August 9, 1954, Serial No. 448,582

Claims priority, application Germany August '12, 1953 '3 Claims. (Cl. 206-.4)

The present invention relates to the design of a vaporizer for the evaporation of metals or alloys especially in high vacua.

In numerous technical processes metals are deposited by evaporation upon other substances, to produce conducting layers on insulating materials, for example, for the manufacture of electrical condensers, to coat cheap material with a corrosion-resistant metallic layer, to obtain a high-quality surface, or else to obtain other efliects, for example, to deposit metallic layers upon the base of selenium dry-disc rectifiers.

Metals, which are to be vaporized especially in high vacua, have hitherto been placed into suitable crucibles which are heated by a heating winding made of resistant wire. It is also known to use conducting substances, for instance carbon, as material for the crucibles, which are heated directly by the passing of a current. Vaporizers having crucibles with a separated heating winding not only are of complicated construction, they also present the disadvantages that in order to insulate the heating wire from the vaporizing crucible, usually made of metal, additional insulating tubes consisting of highly refractory substances are needed, which in most cases are provided with a wrapping of metal or of insulation.

Such an arrangement has a very large heat capacity and consequently excessive amounts of energy are required in order to raise and to keep the temperature of the entire arrangement to a certain level. Consequently the heating wires are excessively strained and a repeated replacement of the heating conductors becomes necessary. On the other hand such Vaporizers require long heating-up periOds and following the switching-off of the current the cooling of the vaporizer also takes a long time. Vaporizers made of conducting material, which are heated by the flow of current need very large currents for heating and are suited only for small amounts of metal.

These disadvantages are avoided by the vaporizer according to this invention. It is characterized in that it is composed of ceramic tubes, rods, or the like, which may preferably be heated with electrical heating conductors, and also serve to insulate the heating conductor wires. in consequence of its small heat capacity the vaporizer can be heated rapidly and no unnecessary large currents have to be used for the heating. Consequently a longer service life and a saving of heating wire results. The vaporizer according to this invention being made of ceramic insulating tubes is also characterized by its great simplicity and can be constructed in any size. Hereby it is not necessary to seal the joints and spaces between the tubes, as in consequence of its high surface tension the melted metal will not run out. It was just this property of the liquid metal, which in heretofore known Vaporizers was considered to be undesirable, and steps were taken to attain a proper moistening of the vaporizers walls.

A vaporizer for metals according to this invention is constructed of a plurality of ceramic insulating tubes, which in a simple manner are kept together by metallic wires, bands, or any other device. The tubes are put ice together and are connected with one another in such a way that a vessel having the shape of a long-stretched trough results. The front sides are preferably closed by bundling-in short rods made of the same material. Instead of these rods, pieces of tube may also be used, if their inner diameter is not too large. A plurality of such vaporize-rs can be arranged in a row or in a plane, so as to permit rapid interchanging, assembly, or disassembly. The heating conductor is preferably pulled through the tubes forming the vaporizer in zigzag fashion and subsequently heats the tube walls directly.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows a vaporizer according to this invention in perspective view,

Fig. 2 demonstrates a horizontal cross-section, located approximately in the region of the metallic melt, and in Figures 3 to 6 illustrate different examples of the assembly of the ceramic tubes.

The vaporizer of Fig. 1 consists of a plurality of ceramic tubes 1, which by the insertion of ceramic rods 2, preferably made of the same material but of shorter length, at the front sides are arranged in a tube-like structure. The bundle of tubes is kept together for instance by two metallic bands 3. The heating conductor is pulled through the three bottom tubes, which are subsequently heated.

Fig. 2 shows the cross-section of the inventive vaporizer of Fig. 1 in the region of the metallic melt 5. The tubes 1 represent the wall of the vaporizer tube and are passed through by the heating conductor 4. The front sides are closed by the short ceramic rods 2. In consequence of the surface tension the liquid metallic melt pulls itself. together in dome-like manner at the open ends as well as at the gaps between the tubes, and consequently the metal will not flow out.

Four embodiments for assembling or bundling the tubes are presented in Figures 3 to 6. The tubes 1 and the rods 2 can be kept together by means of wrapping the same with a wire or band 3 made of an appropriate metal and being simultaneously employed as loop 3a for suspending the vaporizer, as this is indicated at Fig. 3. In the embodiment of Fig. 4 the tubes and rods, of which the vaporizer is constituted, are placed in a piece of sheet metal 6 having a correspondingly designed cutout. At its upper end this piece of sheet metal can be equipped with devices, for example, with a hole 6a, for suspending the vaporizer, or else it may be provided at its lower end with stands for setting it up or mounting it. In the embodiment of Fig. 5 the tube bundle is covered with a cap 7 made of appropriate metal, being simultaneously employed for mounting the vaporizer on a base plate, preferably with a stand 7a.

As demonstrated in Fig. 6 the mounting system for the tube bundle may also consist of appropriately shaped plates 8a and 8b, made of a heat-resistant material, between which the tubes are clamped in.

The embodiments of this invention, which have been demonstrated in the figures do not present the only ones possible. The material used for tubes and mounting system also is determined by the type of application, the temperature strain, the mechanical stresses, etc.

Vaporizers designed according to this invention are characterized by most simple construction and their extremely low heat capacity, and can be applied to advantage in all these processes, in which metals are to be vaporized, particularly in high vacua.

While I have described above the principles of my 3 invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A vaporizer for the evaporation of materials comprising a plurality of ceramic tubes, at least two of said tubes being spaced apart to receive said material to be evaporated, and closure members in the form of short rods arranged to stop up the opening time formed at both ends of the tubes, said rods lying between said tubes in close contact therewith.

'2. A vaporizer according to claim 1 in which the structure consisting of tubes and rods includes clamping members which hold the tubes and rods together.

3. A vaporizer according to claim 1 in which the tubes and rods are placed in end plates having curvatures accommodating the ends thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,584,660 Bancroft Feb. 5, 1952 

1. A VAPORIZER FOR THE EVAPORATION OF MATERIALS COMPRISING A PLURALITY OF CERAMIC TUBES, AT LEAST TWO OF SAID TUBES BEING SPACED APART TO RECEIVE SAID MATERIAL TO BE EVAPORATED, AND CLOSURE MEMBERS IN THE FORM OF SHORT RODS ARRANGED TO STOP UP THE OPENING THUS FORMED AT BOTH ENDS OF THE TUBES, SAID RODS LYING BETWEEN SAID TUBES IN CLOSE CONTACT THEREWITH. 